Ophthalmological display including a device for adjusting focus

ABSTRACT

The invention relates to an ophthalmological display comprising an optical imager ( 10 ) for shaping light beams emitted by an optical element of a light beam generator system ( 20 ) and directing them towards the eye (O) of the wearer as to enable information content (I) to be viewed, said display being fitted with a device for adjusting focusing by adjusting the length of said light beams between said element and the imager. According to the invention, the generator system comprises a stationary part ( 21 ) referred to as a stationary plate, to which said optical element is connected by a moving connection ( 22 ) that is adjustable by an actuator device.

RELATED APPLICATION

The present application is a national phase application ofPCT/FR2005/050474, which in turn claims the benefit of priority fromFrench Patent Applications No. 04 51425, filed on Jul. 2, 2004, theentirety of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an ophthalmological display comprisingan ophthalmic lens and an optical imager for enabling information of theimage or multimedia type to be projected. The term “lens” is used hereinto mean an optical system suitable in particular for being positioned ina frame for eyeglasses.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 5,886,822 discloses an ophthalmic lens presenting aprojection insert. Such a projection insert is constituted by an opticalimager for shaping light beams delivered by an electronic and opticalsystem for generating light beams from an electronic signal, of theminiature screen, laser diode, or light-emitting diode (LED) type. Theoptical semiconductor directs light beams towards the eye of the wearerin order to enable information content to be viewed.

An example of a prior art display is shown in its environment in greaterdetail in FIG. 1.

By way of example, the optical imager is of the same type as describedin above-mentioned U.S. Pat. No. 5,886,822.

An electronic signal carrying information is brought to a miniaturescreen 1 by a cable 7. On the basis of this signal, the miniature screen1, illuminated by a background projector 2, generates a pixel imagecorresponding to the information. By way of example, it is possible touse a “Kopin Cyberdisplay 320 color” screen generating images comprising320×240 pixels and having dimensions of 4.8 millimeters (mm)×3.6 mm. Thescreen 1 is held by a mechanical interface 3 in position relative to theoptical imager 5. A protective shell 4 protects all or part of theassembly.

The optical imager 5 comprises a propagation prism 5 a, a counter prism5 b, a quarterwave plate 5 c, and a spherical Mangin mirror 5 d. Thespherical Mangin mirror is a plano-spherical lens whose spherical facehas been made reflecting by aluminum plating treatment or theequivalent.

The imager 5 also includes polarization separator treatment 6 which maybe implemented in the form of a deposit of thin layers either on thepropagation prism 5 a or on the counter prism 5 b, or by means of a filmstuck between the two above-mentioned elements.

The imager 5 is embedded in a molded lens 9 and the housing is disposedon one side of the lens 9. On the same principle, the housing could beplaced facing forwards at the back of the lens, an injection elementforming a 90° reflector element then being included in the lens.

The word “lens” is used in particular for an optionally correcting lenssuitable for mounting in a frame for eyeglasses. This ophthalmic lenspresents conventional functions such as correcting eyesight, andcoatings against reflection, dirtying, scratching, etc.

In order to enable focusing to be adjusted so as to adjust the viewingdistance of the information image and consequently adjust the image sothat the wearer can see it in sharp and comfortable manner, the lens 9is secured to a plate 10 carrying two rods 10A and 10B on which thehousing 4 is engaged in slidable manner. During this adjustment, thehousing is engaged manually to a greater or lesser extent on the sliderods to adjust the distance D, and thereafter it is held in position bya transverse screw (not shown).

That type of device for adjusting focusing raises the followingtechnical problems.

Depending on how it is adjusted, the overall size of the display varies.This can lead to constraints in its design.

This type of device inevitably leads to a considerable amount of slackbetween the slide rods and the housing, which harms the accuracy of thedisplay.

The housing is generally made of plastics material and the plate 10together with its rods 10A and 10B are made of metal. This results tothe housing wearing quickly and further increasing the slack and lack ofprecision of the display.

Finally, in that prior art, the adjustment is performed manually in thesense that the wearer needs to take hold of the housing and cause it toslide along the rods until proper focus is obtained. Naturally, such anarrangement is not very accurate and is not very comfortable in use,being poorly adapted to everyday use that is not experimental.

OBJECTS AND SUMMARY OF THE INVENTION

The invention solves those problems by proposing a display of overallsize that does not vary and that is comfortable to handle while makingan adjustment.

To do this, the invention provides an ophthalmological displaycomprising an optical imager for shaping light beams emitted by anoptical element of a light beam generator system and for directing thebeams towards the eye of the wearer so as to enable information contentto be viewed, the display being fitted with a focus adjustment devicefor adjusting the length of said light beams between said element andthe imager, said imager being integrated in a lens for mounting in aframe for eyeglasses, the display being characterized in that saidadjustment device is internal to a housing containing said light beamgenerator system, and in that said generator system includes astationary part referred to as a stationary plate, having connectedthereto said optical element via a moving connection that is adjustableby an actuator device.

In a preferred embodiment, said optical element is secured to a secondplate connected to the stationary first plate by said moving connection.

And advantageously, said actuator device is external to said housing.

In the invention, the housing serves only to provide protection againstattack from the surrounding medium, from impacts and from flattening,and also to provide a sealing function, and the housing is preferablyremovable, being put into place last. The hosing is advantageously putinto place by being secured to the stationary plate or part.

Preferably, said connection is an elastically-deformable element.

The dimensional and positioning characteristics of this deformableelement can be calculated by finite element type calculation methods inorder to determine the characteristics of the displacement.

In a particular embodiment, said elastically-deformable element isconstituted by a deformable fork.

In a first variant, said actuator device is constituted by a knobprovided with an eccentric cylinder, said knob being mounted to turnrelative to a stationary portion of the housing and said eccentriccylinder being in abutment against said second plate.

This characteristic presents the advantage of being suitable for beingautomatically prestressed so as to avoid any slack and determine theamount of force that needs to be exerted on the knob so as to improveuser comfort and avoid any damage. Furthermore, by turning the knobcontinuously in the same direction, it is possible to pass through alldesired positions on the path of the moving plate. Finally, because ofits relatively large size, a knob is particularly adapted to achievingvery small displacements accurately.

In a second variant, said actuator device is constituted by a screwscrewed into a stationary portion of the housing and in abutment againstsaid second plate.

Advantageously, an adapter is in a reference position relative to theimager and receives said generator system together with its focusadjustment device by engagement of at least two studs.

This embodiment presents the advantage of decoupling the various opticaland mechanical functions. Each part performs one function only, thusenabling maximum precision to be obtained, whether mechanically oroptically. The adapter ensures that the device is positioned relative tothe imager.

And preferably, said adapter is secured to said stationary plate.

The adapter can be secured to the lens by adhesive, screw-fastening, orany appropriate means.

The connection between said focus adjustment device and said adapter maybe releasable.

Said optical element is preferably a miniature screen.

In which event, said stationary plate advantageously carries anassociated optical component.

In a preferred application, said imager is integrated in a lens.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below in greater detail with reference tofigures that merely show a preferred embodiment of the invention.

FIG. 1 is a plan view of a prior art display and is described above.

FIG. 2 is a diagrammatic plan view of a display in accordance with theinvention.

FIG. 3 is a face view of a device for adjusting the focus of a displayin accordance with the invention.

FIG. 4 is a plan view of the same focus adjustment device.

FIG. 5 is a perspective view from behind of the same focus adjustmentdevice.

FIG. 6 is a perspective view from beneath of the same focus adjustmentdevice.

FIG. 7 is a diagrammatic view of a first variant actuator device formingpart of a display in accordance with the invention.

FIG. 8 is a diagrammatic view of a second variant actuator deviceforming part of a display in accordance with the invention.

DETAILED DESCRIPTION

The display is thus shown diagrammatically in FIG. 2.

This ophthalmological display comprises an optical imager 10 for shapinglight beams emitted from a miniature screen 20 placed in a housing 30 soas to direct the light beams towards the eye O of the wearer in order toenable information content to be viewed. The imager 10 is of the sametype as that shown in FIG. 1. In contrast, the housing 30 is placedagainst the rear face of the lens 11 that carries the imager. Areflector element 12 for reflecting the light beam through 90° istherefore also integrated in the lens so as to direct said beamlongitudinally to the imager 10.

Nevertheless, as will readily be understood, the invention appliesequally to an imager of the type shown in FIG. 1 or to an imager of thetype shown in FIG. 2.

Firstly, an adapter 13 is bonded accurately on the lens by means ofadhesive, and then the adjustment device described below is secured tothe adapter. The adapter 13 has two accurately perpendicular sides thatenable it to be positioned accurately facing the imager and moreprecisely facing the reflector element 12.

The adjustment device comprises a stationary plate 21 having theminiature screen 20 secured thereto by an adjustable movable connection22. It also supports optical components 23 shown diagrammatically. Theadapter 13 is secured to the stationary plate 21.

By adjusting the connection 22, e.g. from position P1 to position P2 inwhich the screen is drawn in dashed lines, the length of the light beamsbetween the screen and the imager is modified, and thus focus isadjusted enabling the image I1 to be viewed at a distance from the eye Othat is greater as represented by the dashed-line image I2.

This focus adjustment device is shown in greater detail in a preferredembodiment in FIGS. 3 to 6. In these figures, the housing 30 is omitted.

The adapter 13 is a substantially square slab whose outside face 13A isto be adhesively bonded to the lens. This adapter 13 has the stationaryplate 21 secured thereto by three studs 13B that are engaged incorresponding orifices in the adapter, as can be seen in FIG. 5. Thesethree engaged studs enable relative positioning to be provided that isexact. Furthermore, the adapter 13 includes a snap-fastening peg 13Cthat snap-fastens between two resilient rods 21A secured to thestationary plate 21 and enabling the plate to be held releasablyrelative to the adapter 13.

The stationary plate 21 includes the optical component downstream fromthe miniature screen, and more precisely in this example it includes alens 23. This lens 23 redirects the light beams F that it receives fromthe screen 20 via its face 23A towards the imager inserted in theeyeglass lens via its face 23B.

The screen 20 is carried by a second plate 24 connected to thestationary first plate 21 by a moving connection constituted by anelastically-deformable element so as to enable the distance between thescreen 20 and the inlet face 23A of the lens 23 to be adjusted.

To do this, the stationary plate 21 has a base 21B that is substantiallyparallel to the axis of the inlet face 23A of the lens, and a lug 21Cperpendicular to said base and placed on one of its sides. This lug 21Cis connected to the first branch 22A of a deformable fork 22 whose otherbranch 22B is connected to a lug 24C of the second plate 24. Theseconnections can be seen particularly clearly in FIG. 6. The lugs 21C and24C have respective slots at their ends receiving respective pegscarried by each of the branches 22A and 22B.

These branches 22A and 22B can move relative to each other in thedirection of arrow F under drive from an actuator device external tosaid housing, and constituted in this example by a knob 25.

Although visible only from the outside in FIGS. 3 to 6, the knobactuator device 25 is represented diagrammatically in FIG. 7 in a mannerthat can be understood by the person skilled in the art.

This figure shows the stationary plate 21, the moving second plate 24,and the elastically-deformable element 22.

The knob 25 can be turned about its axis of rotation A and it carries acylindrical eccentric 25A which is in abutment against a face of thesecond plate 24. As shown clearly in FIG. 7, when the knob is turned,this cylinder pushes the second plate 24 and then releases it, whereuponthe second plate returns in the opposite direction because of theresilience of the connection 22 and remains in abutment against thecylinder 25A.

In a variant, it is possible to use a screw instead of a knob, and thisis shown diagrammatically in FIG. 8, or more generally it is possible touse an adjustable abutment. A screw 26 is then turned in a tapped boresecured to the stationary plate 21 and its end comes into abutmentagainst a face of the moving plate 24.

Although the housing 30 is not shown in FIGS. 3 to 6, the stationaryplate 21 and the second plate 24 are both contained in the housing, asshown diagrammatically in FIG. 2.

In the embodiment described, it is the miniature screen that constitutesthe optical element connected to the stationary plate by a movingconnection that is adjustable by means of an actuator device external tosaid housing.

In the context of the invention, it could be the optical component asconstituted for example by the lens 23 or the screen-plus-lens assemblythat occupies a position that is adjustable by means of the adjustablemoving connection. In all circumstances, the purpose is to vary theoptical distance, i.e. the length of the light beams processed by thedisplay.

1. An ophthalmological display comprising: an optical imager for shapinglight beams emitted by an optical element of a light beam generatorsystem and for directing the beams towards an eye of a wearer so as toenable information content to be viewed, the display being fitted with afocus adjustment device for adjusting the length of said light beamsbetween said element and the imager, said imager being integrated in alens for mounting in a frame for eyeglasses, wherein said adjustmentdevice is internal to a housing containing said light beam generatorsystem, and in that said generator system includes a stationary partreferred to as a stationary plate, having connected thereto said opticalelement, via a moving connection that is an elastically-deformableelement and is adjustable by an actuator device.
 2. A display accordingto claim 1, wherein said optical element is secured to a second plateconnected to the stationary first plate by said moving connection.
 3. Adisplay according to claim 1, wherein said actuator device is externalto said housing.
 4. A display according to claim 1, wherein saidelastically-deformable element is a deformable fork.
 5. A displayaccording to claim 1, wherein said actuator device is a knob providedwith an eccentric cylinder, said knob being mounted to turn relative toa stationary portion of the housing and said eccentric cylinder being inabutment against said second plate.
 6. A display according to claim 1,wherein said actuator device is a screw screwed into a stationaryportion of the housing and in abutment against said second plate.
 7. Adisplay according to claim 1, wherein an adapter is in a referenceposition relative to the imager and receives said generator systemtogether with its focus adjustment device by engagement of at least twostuds.
 8. A display according to claim 7, wherein the connection betweensaid system and said adapter (13) is releasable.
 9. A display accordingto the claim 1, wherein said adapter is secured to said stationaryplate.
 10. A display according to claim 1, wherein said optical elementis a miniature screen.
 11. A display according to claim 1, wherein saidstationary plate carries an associated optical component.